1. Field of the Invention
The present invention relates to a process for the preparation of cis-platinum(II) complexes of 1,2-cyclohexanediamine isomers that serve as active components of carcinostatic drugs.
2. Background Art
Platinum compounds represented by formula I ##STR2## are generally known to have carcinostaticity. They have conventionally been prepared by the following steps: reacting K.sub.2 Pt(II)X.sub.4 (X is Cl or Br) with a 1,2-cyclohexanediamine isomer to form an intermediate compound represented by formula II ##STR3## dissolving the intermediate compound in water under boiling; adding thereto a solution of AgNO.sub.3 in an amount of twice the mol equivalent of the intermediate compound represented by formula II so as to cause chlorine or bromine contained in the compound to precipitate in the form of silver chloride or bromide; separating the precipitates through filtration; and adding a dibasic organic acid to the filtrate.
However, the platinum compounds represented by formula I obtained through the customary process contain as an impurity about 0.1-5% of a dihydroxoplatinum(IV) complex--a platinum compound represented by formula III--which is produced through oxidation of the platinum compounds represented by formula I. ##STR4##